1. Field of the Invention.
This invention relates to the handling of a relatively low temperature liquid, such as ammonia, and more particularly to an indirect system of heat exchange between it and a waste heat source, such as water, which is available at an appropriate temperature in relatively large quantity. The temperature of the ammonia is raised, without changing it from its liquid state, to facilitate its transportation. Provision is made for continuously monitoring the temperatures of the ammonia and the water to accomplish the desired temperature rise and avoid freezing of the water. 2. Description of the Prior Art.
When it is necessary to transport liquid ammonia, its temperature must be raised from approximately -28.degree. F to approximately 40.degree. F in order that it may be shipped in railway tank cars and tank trucks. In the past the heating has been accomplished by the burning of fuel oil and gas.
One of the objects of the invention is to provide for the raising of the temperature of liquid ammonia by heating means which does not require a high temperature heat, such as that obtainable from the burning of fuels, but which, on the other hand, is obtainable from a waste heat source such as a storage pool of water, heated by solar absorption, exhaust steam, or process work in order that energy may be conserved.
The prior art discloses systems for providing super heated gaseous fluid from a low temperature liquid supply in which a closed system is employed. See, for example, the U.S. Pat. No. to Bivins, 3,986,340. Other examples of the prior art include U.S. Pats. to Arenson No. 3,712,073, to Karbosky, No. 3,345,872, to Kals, No. 3,421,574, to Linde et al, No. 3,535,210, and to Ogura et al, No. 3,906,261. Some of these disclose various condition responsive control means whose stated purpose is to avoid or reduce the likelihood of freezing of the water which is used for heating.